Tannerus is an impact crater in the southern lunar front side, east of Jacobi and southwest of Asclepi. The rim is eroded, the crater floor flat.
The crater was first named in 1651 by Giovanni Riccioli after the Ingolstadt controversial theologian and Jesuit Adam Tanner whose main historical merit is seen today in its fundamental criticism of the persecution of witches. The Jesuit Riccioli justified the naming but with Tanners rendered to the theological discussion of Lutheranism, in his words, " the heretics ".
Beer and Mädler painted in their selenography of 1837 the name of the " furious heretic hunter ", which they thus reasoned that it could not be possible to know the crater Riccioli have exactly meant. The selenograph Edmund Neison bore the name again. 1935, the crater was officially named by the IAU according to Tanner. The secondary craters received their IAU names 2006.